Vulcan Inc. Founder and Chairman Paul Allen attends Time's 100 Most Influential People in the World Gala in New York. Allen, the billionaire owner of the Trail Blazers and the Seattle Seahawks and Microsoft co-founder, died Monday, Oct. 15, 2018 at age 65. (AP Photo/Evan Agostini, File)

He was a brilliant mind, a visionary who helped change the course of the 20th Century and the very future of technology. 

Seattle native Paul Allen co-founded Microsoft with Bill Gates after the pair became friendly in high school, and Allen’s philanthropic zeal went on to mirror that of Gates, with the former pledging to give away half of his wealth and spending $95million on charitable causes last year alone.

Allen did, however, also take the time to enjoy the spoils of his fortune himself, as a brief glimpse of his homes, yachts, planes, art collection and fabulous lifestyle make glaringly apparent.

The fortune of the 65-year-old, who died Tuesday after a battle with cancer is estimated to be $20.3 billion (R285bn). 

He never married or had children; his immediate surviving relatives are his sister, Jody, and her three adult children, who joined him on some of his global escapades over the years.

They lived near him in suburban Seattle, Washington; Allen owned at least nine mansions on wealthy Mercer Island, with his main residence listed as a 10,000-square-foot pile boasting a mammoth indoor pool area complete with a slide. 

One of the other mansions housed his late mother, who died six years ago at the age of 90, and other relatives lived nearby, and his properties also include a floating helipad off the island.

Allen also owned an entire island off the coast of Washington, buying undeveloped and uninhabited Allan Island in 1992 with plans to develop a dream home there, but the absence of existing infrastructure and other problems prompted him to sell the land for $8 million in 2013.

Allen spent a lifetime re-investing in his home city, ensuring that his favorite Seattle movie theater, Cinerama, remained open and modernised. He also bought the Seattle Seahawks football team in addition to the Portland Trail Blazers basketball team one state away in Oregon.

His property portfolio, however, extended far beyond the Pacific Northwest. Allen purchased former estate The Enchanted Hill in 1997 in the swanky Los Angeles suburbs for $20 million; the Spanish Colonial home on 24 acres had been built in the 1920s for screen stars Frances Marion and Fred Thomson. Allen drew ire when he demolished the mansion full of Hollywood history, however, and terraced the land, leaving it otherwise undeveloped. 

He put it up for sale in July for $150 million.

He certainly had other housing options in California; Allen also previously owned a white-walled contemporary home on a stretch of Malibu known as ‘Billionaire’s Beach.’ He bought the property in 2010 for $25 million but sold it to Les Moonves in 2014 for a $3 million profit – because he ‘hated the sound of the ocean,’ according to a New York Post source.

Aside from that, the billionaire also bought a 12,952 square foot Mediterranean-style mansion in 1997 in Beverly Hills – complete with a funicular from the pool deck to the tennis court.

And he didn’t leave Northern California out, either; Allen purchased a whopping 8-bedroom, 9.5-bathroom home in 2013 in the San Francisco Bay Area community of Atherton – one of the nation’s most expensive zip codes. The 22,000-sq-ft residence also included a spa, a home movie theater, seven fireplaces and a 5-car garage.

Allen didn’t limit his property purchases to the West Coast, however; he also splashed out on an estate in Hawaii, a $7.5 million, 10-acre property known as the Thurston Estate in Kailua-Kona, a region on the west coast of Hawaii’s Big Island. 

The property includes a $12,000-sq-foot main house, an employee residence, beach house, boat shed and a private harbor.

The tech billionaire also invested in property in the West, splashing out on what used to be a sheep ranch in Tetonia, Idaho in 1993. The property operated as a luxury mountain lodge for some time called Teton Ridge Ranch, though it closed for business nearly ten years ago.

A bit further afield, Allen also made property investments in New York City. He bought an 18-room 11th floor apartment in 1996 at 4 East 66th Street, a coveted Fifth Avenue address, for $13.5 million. 

On top of that, he spent $25million in 2011 for the penthouse at the same address, a property featuring significant roof terrace space. 

The two apartments combined, one Manhattan real estate expert said at the time, would provide Allen with ‘a huge duplex penthouse.’ 

And those were only his US properties. Allen also boasted a home in one of London’s swankiest areas – Holland Park – where other residents include notable billionaires like Richard Branson. In France, he was the proud owner of historic Villa Maryland, built in 1904 at the behest of a friend of King Edward VII. 

The sprawling estate in the Cote d’Azur played host to Allen’s celebrity parties and was even the site where Brad Pitt and Angelina stayed in 2006 ahead of the birth of Shiloh; the family returned with their entourage of children, nannies and bodyguards two years later.

All of those eye-watering mansions, however, are only the tip of the iceberg; Allen’s veritable fleet of floating homes are just as impressive. 

The billionaire bought superyacht Tatoosh in 2001, valued at $160million; the vessel carries a helicopter, a sail boat and several other boats. It can sleep 20 guests in 10 cabins, attended to by 35 staff in 16 cabins.

Next up was one of world’s most extravagant yachts, Octopus, which Allen spent $200 million to build before its official launch in 2003. 

The 414-foot vessel features a pool, two helicopters, a movie theater, basketball court, recording studio and accommodations for 26 guests in 41 suites. Allen famously hosted Cannes and other parties aboard the ultra-luxurious yacht, and often – as a huge rock-n-roll fan – treated guests to his own musical performances.

In addition, it wasn’t unheard of for Allen to lend out Octopus for search and rescue operations or scientific studies. In the same vein, another addition to Allen’s floating empire was RV Petrel, a 250.8-foot research vessel he bought from a subsea engineering and construction company. 

He had the vessel completely refitted last year, and the RV Petrel has already discovered wrecks of the USS Indianapolis and the USS Lexington.